Lubricating oil composition



United States Patent Office 3,523,082 Patented Aug. 4, 1970 U.S. Cl.25232.7 3 Claims ABSTRACT OF THE DISCLOSURE Lubricating oil compositionshaving improved water tolerance and rust inhibiting properties areobtained by incorporating in a petroleum lubricating oil a combinationof (l) a calcium salt of a preferentially oil-soluble sulfonic acid, (2)a sodium salt of a preferentially oilsoluble sulfonic acid, and (3)butyl Cellosolve.

BACKGROUND OF THE INVENTION Lubricating oil compositions, particularlyadapted for use in internal combustion engines as crankcase oils,commonly have incorporated in a base petroleum lubricating oilwell-known additives such as a zinc dialkyldithophosphate, apolymethacrylate viscosity index improver, a pour point depressor, suchas a wax alkylated naphthalene and an anti-foam agent, such as asilicone polymer. Such compositions are often used as so-calleddriveaway oils. I

One of the problems encountered with the conventional crankcase oilcomposition is the inability of such corn positions to tolerate waterwhich invariably enters the crankcase of internal combustion engines.That is, the lubricating oil composition does not have the property ofholding water in suspension, and consequently when the engine is notbeing operated such water drops out of the oil composition causingrusting and/or corrosion.

SUMMARY Internal combustion engine crankcase lubricating oils having ahigh water tolerance and inhibiting anti-rust properties are obtained,in accordance with the present invention, by incorporating in apetroleum lubricating oil from about 4.0% to about 6.0% of a calciumsalt of a preferentially oil-soluble petroleum sulfonic acid, 0.5% of asodium salt of a preferentially oil-soluble petroleum sulfonic acid and0.5% butyl Cellosolve, the percentages beingbased on the totalcomposition of the crankcase lubricating oil composition.

A typical crankcase lubricating oil formulation which meets the requiredperformance specifications is set out below, in which the proportionsare given in weight percentages:

ponent when the crankcase lubricating oil composition is to be usedunder relatively mild operating conditions, but is necessary when thecrankcase oil is requiied to pass the L-38 Engine Test, also referred toas CLR- 38 Engine.Test. This test is designed to evaluate hightemperature oxidation stability of a lubricating oil composition. I I

The preferentially oil-soluble calcium and sodium petroleum sulfonatesemployed are the substantially neutral salts of preferentiallyoil-soluble sulfonic acids having molecular weights from about 300 toabout 500. The sulfonic acids are Well known to those skilled in theart; especially usable are the preferentially oil-soluble sulfonic acidsand preferably the preferentially oil-soluble petroleum sulfonic acids,referred to in the art as mahogany acids. The sulfonic acids includesuch mahogany acids, unsaturated paraffin wax sulfonic acids, petrolatumsulfonic acids, monoparafiin wax-substituted naphthalene sulfonic acids,diparaffin Wax-substituted phenol sulfonic acids, wax sulfonic acids,petroleum naphthalene sulfonic acids, fuel oil substituted-benzenesulfonic acids (synthetic alkyl aryl sulfonic acids) diphenyl ethersulfonic acids, diphenyl ether disulfonic acids, naphthalene disulfidesulfonic acids, naphthalene disulfide disulfonic acids, diphenyl aminedisulfonic acids, diphenyl amine sulfonic acids, thiophene sulfonicacids, alpha-chloronaphthalene sulfonic acids, cetyl chlorobenzenesulfonic acids, cetylsulfonic acids, cetyl-phenol disulfide sulfonicacids, cetylphenol monosulfide sulfonic acids, cetoxy capryl-benzenesulfonic acids, dicetyl thianthrene sulfonic acids, dilauryl betanaphthol sulfonic acids, di-capryl nitro-naphthalene sulfonic acids;hydroxy substituted parafiin wax sulfonic acids, tetra-isobutylenesulfonic acids, tetra-amylene sulfonic acids, ohloro-substitutedparafiin wax sulfonic acids, nitroso parafiin wax sulfonic acids,cetyl-cyclopentyl sulfonic acids, lauryl-cyclo-hexyl sulfonic acids,monoand poly-wax substituted cyclohexyl sulfonic acids, etc. Otherusable preferentially oil-soluble sulfonic acids are well described inthe art, for example, see U.S. 2,616,904; U.S. 2,626,207; and U.S.2,767,209.

It is preferred to use preferentially oil-soluble sulfonic acids havingmolecular weights of from about 300 to about 500, derived from variouspetroleum fractions such as turbine oil, mineral lubricating oil, whiteoil distillate's, heavy oil petroleum waxes (e.g., petrolatum parafiinwax and mixtures of various hydrocarbon wax fractions), etc. Suchsulfonic acids are well known to the art. They can be obtained forexample, by treating the petroleum fraction with concentrated or fumingsulfuric acid or sulfur trioxide; sulfonic acids derived in this mannerare commonly called mahogany acids. The calcium and sodium sulfonatesare prepared from such sulfonic acids by conventional neutralizationtechniques, well known in the art, employing basic compounds such ascalcium oxide, calcium hydroxide and sodium hydroxide to neutralize thesulfonic acids.

The zinc dialkyldithiophosphates when employed in the composition of thepresent invention, are well-known salts of the general formula:

in which R and R are the same or different alkyl radicals. Such alkylradicals may contain from 1 to about 15 carbon atoms; however, when oneof the alkyl radicals contains less than 6 carbon atoms, the other alkylradical should contain at least 6 and preferably at least 8 carbonatoms. The dialkyldithiophosphates are prepared by the reaction of P 5with alkanols having the desired number of carbon atoms; the alcoholsbeing preferably primary alcohols or a mixture of primary and secondaryalcohols. Examples of specific zinc dialkyldithiophosphates suitable foruse in the composition herein-described are zinc dioctyldithiophosphate, zinc isopropyl n-hexyl dithiophosphate, zinc n-butyldecyl dithiophosphate, zinc isopropyl nonyl I ([711 CH2-C wherein R isan alkyl group or a mixture of alkyl groups containing from about 4 toabout carbon atoms, and n is a number providing a molecular Weight ofthe polymer of about 10,00030,000. Various polymethacrylates of thistype are known which possess pour depressant and viscosity indeximproving properties. A very satisfactory material of this type is apolymer of the lower C alkyl methacrylate monomers. A commercialpolymethacrylate, which is primarily a viscosity index improver, is soldunder the trade name Acryloid 710 wherein R comprises about 50 percentlauryl and 50 percent octyl groups and the molecular weight is about10,000 to 20,000. Another commercially-available polymethacrylate isAcryloid 615 wherein the alkyl groups are a mixture of groups derivedfrom oxo-alcohols and the polymer has a molecular weight of about 10,000to 30,000. Another suitable polymethacrylate is available under thetrade name Acryloid 150, in which the alkyl group is predominantly amixture of 50% cetyl, lauryl and 25% octyl groups and which has amolecular weight of about 10,000-15,000.

The pour point depressor used is a wax alkylated naphthalene which isWell known as a pour point depressor for lubricating oils. Thesematerials are in general prepared by chlorinating paratfin wax andcondensing the chloro- Wax with naphthalene. A preferred product is thatprepared by the process described in US. Pats. 1,963,917 and 1,963,918.Wax alkylated naphthalene products are marketed under trade names suchas Pourex and Paraflow. Other commercial pour point depressors such asthose marketed under the trade name Santapour can also be used.

The silicone polymer foam inhibitor can be any of the well known liquidsilicone polymers commercially available as anti-foam agents, such asdimethyl silicone polymer, diethyl silicone polymer, methyl alkylsilicone polymer, diphenyl silicone polymer, phenyl ethyl siliconepolymer, methyl phenyl silicone polymer and other dihydrocarbon siliconepolymers such as disclosed in US. Pat. No. 2,375,007.

The lubricating oil base is a petroleum oil in the lubrieating oilviscosity range, i.e. from about 80 SSU at 100 F. to about 300 SSU at210 F. and preferably having a viscosity of from about 150 to about 190SSU at 100 F. The oil is preferably one which has been solvent extractedwith solvents well known in the art, such as, for example, phenol,furfural, Chlorex liquid S0 nitrobenzene etc. Synthetic lubricating oilswell known in the art may also be used.

Additives, in addition to those hereinabove mentioned, may beincorporated in the lubricating oil composition, such as for exampleE.P. agents, anti-wear agents, etc. Such additives are Well known in theart.

PREFERRED EMBODIMENT The following preferred formulation is illustrativeof the present invention.

Component:

Substantially neutral calcium salt of preferentially oil-solublepetroleum sulfonic acid 6.0%

Substantially neutral sodium salt of preferentially oilsoluble petroleumsulfonic acid 0.5%

Butyl Cellosolve0.5%

Zinc isopropyloctyl dithiophosphatel.2%

Methacrylate alkyl ester polymerAcryloid 615" 3 Wax alkylatednaphthalene-PoureX2.0%

Silicone polymer foam inhibitor5 p.p.m.

Solvent extracted S.A.E base petroleum oilSSU at 100 F. of 17089.3%

1 Molecular weight of sulfonic acidabout 440.

2 Molecular Weight of sult'onic acidabout 4S0.

Alkyl group derived from oxo-alcohols; molecular Weight of polymerabout; 10,000.

One of the most rigid specifications for crankcase lubricating oils foruse as drive-away engine oils is that required by InternationalHarvester Specifications B21HR. The above preferred formulation wassubjected to the various tests required by this specification with thefollowing results:

Test Formulation specification Viscosity at 100 F. SSU 191 Viscosity at210 F. SSU 46. 6 3 43. 5 Viscosity at 0 F. SSU 10. 200 2 12, 000 IHB T-Q5 Rust Test hrs Pass Pass IHBT-7 Water Tolerance, 1% H20 5 7 0.0 1 0. 5

1 Not specified in specifications.

2 Maximum.

3 Minimum.

4 Extrapolated 5 Refers to International Harvester Specifications.

5 One percent Water is shaken into a cc. sample which then is allowed tostand quiescent for 7 days. Not more than 0.5 ml. dropout of water ispermitted.

7 Bright.

The importance of the named components, both in kind and concentration,to obtain the necessary results with respect to Water tolerance and rustinhibition is illustrated by the data in the following table:

Sample number Component 1 2 3 4 5 6 Substantially neutral calcium saltof preferentially oil-soluble petroleum sulfonic acid 6. 0 6.0 4. 0 4. 04.0 4. 0 Substantially neutral sodium salt of preferentially oil-solublepetroleum sulfonic acirl 0.5 0. 5 0.5 Butyl cell0solve 0. 5 0.5 Zincisopropyloctyl dithiophosphate- 1. 2 1. 2 1. 2 Acryloid 615 0. 5 0. 5 0.5 Pourex" 2. 0 2. 0 2. 0 Silicone polymer foam inhibitor (p.p.m.) 5 5 5Extracted SAE 10 base petroleum 00.. 89.3 80. 8 91. 3

est:

Water tolerance test Pass Fail Fail Oil appearance... Bright CloudyBright Dropout, percent 0. 0 0. 5 Separate Rust test Pass Pass pass theL-38 Test.

The above data illustrate the importance of the proper ratio of thenamed components. Sample No. 1, the preferred formulation, passed eachtest. Formulations without the sodium sulfonate or butyl Cellosolve, asin Sample Nos. 2 and 5, failed to pass the water tolerance test. Thepresence of the zinc dialkylidthiophosphate in the formulation requiresan increased level of calcium sulfonate as demonstrated by Sample Nos.1, 3 and 4. Sample No. 1 with 6% of the calcium sulfonate passed alltests, including the L-38 Engine Test; reducing the amount of calciumsulfonate to 4.0% gave a product which failed the Water Tolerance Testbut passed the -L38 Engine Test. On the other hand, Sample No. 4containing 4% calcium sulfonate but no zinc dialkyldithiophosphatepassed the Water Tolerance Test, but would fail the L-38 Engine Test.Increasing the amount of sodium sulfonate, as in Sample No. 6, gives aproduct having satisfactory water tolerance but fails in the rust test;the same is true if the butyl Cellosolve is increased excessively.

Percentages given herein and in the appended claims are weightpercentages unless otherwise noted.

We claim:

1. The lubricating oil composition comprising essentially the followingcomposition in which the proportions are given in weight percentage:

Substantially neutral calcium salt of a preferentially oilsolublesulfonic acid4.06.0%

Substantially neutral sodium salt of a preferentially oilsolublesulfonic acid0.5%

Ethylene glycol monobutyl ether-0.5%

Poly (C -C alkyDmethacrylate having a molecular Weight of about 10,000to about 30,0000.5%

Wax alkylated naphthalene pour point depressor-2.0%

Silicone polymer foam inhibitor-5 p.p.m.

Lubricating oilRemainder 2. The lubricating oil composition of claim 1wherein (a) the preferentially oil-soluble sulfonic acid is a petroleumsulfonic acid having a molecular weight of from about 300 to about 500,(b) the wax alkylated naphthalene is a parafifin wax alkylatednaphthalene, and (c) the lubricating oil is a petroleum lubricating oilhaving a viscosity in the range of from about SSU at F. to about 300 SSUat 210 F.

3. The lubricating oil composition comprising essentially the followingcomposition:

References Cited UNITED STATES PATENTS 2,807,590 9/1957 McDonald et al.25233 2,943,052 6/1960 Caryle et al. 25233 3,001,940 9/1961 Watson etal. 25232.7

DANIEL E. WYMAN, Primary Examiner I. VAUGHN, Assistant Examiner US. Cl.X.R.

